Traditionally in frequency synthesis systems, Si bipolar or GaAs technology is used for high-frequency circuits, such as prescalars, while CMOS technology is used for lower frequency circuits, such as phase-locked loops. This mixture of different technologies requires costly interface circuits. BiCMOS technology (wherein both bipolar and CMOS transistors are integrated on the same IC) offers a possible solution, but generally at a higher cost, using contemporary fabrication processes. As CMOS dimensions continue to scale down, however, high-frequency CMOS circuits may be designed and integrated with lower frequency CMOS circuits on the same IC simplifying system interfaces and reducing system costs.
In "Multigigahertz CMOS Dual-Modulus Prescalar IC", Hong-Ih Cong, et al., IEEE Journal of Solid State Circuits, October 1988, a low-power CMOS dual-modulus prescalar IC is described. That circuit, although effective at high frequencies, has a high power drain due to contention problems at several nodes. Such contention problems occur in circuits when one circuit device is attempting to pull a node toward a certain logic state, another circuit element is attempting simultaneously to pull the node to the opposite logic state. Such contention problems cause greater current (and hence power) drain. Power drain problems are highly undesirable in portable radio applications because of the restraints on the battery contained therein.